Scalable MIMO-OFDM PHY for high throughput WLANs

Abstract

A MIMO-OFDM system may use different types of space-frequency code matrices for encoding data on multiple substreams for transmission on multiple antennas. The system may utilize a MIMO-OFDM frame format that includes additional long training OFDM symbols for training additional antennas and for link adaptation and a header with an additional SIGNAL symbol to indicate MIMO-OFDM-specific information.

1. A transceiver comprising:
 a transmit section configured to generate signals for transmission on a plurality of antennas at a predetermined spatial multiplexing rate r s , the transmit section including:
 a code module configured to generate i) a first vector for a tone in an orthogonal frequency-division multiplexing (OFDM) symbol from a second vector corresponding to the tone and ii) a space-frequency code matrix, the second vector including a number of modulated symbols corresponding to the predetermined spatial multiplexing rate r s , 
 wherein the code module is configured to generate the space-frequency code matrix such that a Frobenius norm of the space-frequency code matrix is constant for all tones. 
 
 
     
     
       2. The transceiver of  claim 1 , wherein the plurality of antennas comprise M T  antennas and the predetermined spatial multiplexing rate r s  has a value between 1 and M T , and
 wherein the space-frequency code matrix comprises an M T ×r s  matrix. 
 
     
     
       3. The transceiver of  claim 2 , wherein the first vector includes M T  symbols. 
     
     
       4. The transceiver of  claim 1 , wherein the OFDM symbol includes a plurality of tones, and
 wherein the code module is configured to generate the space-frequency code matrix such that the OFDM symbol is transmitted with equal transmit power per tone on the plurality of antennas. 
 
     
     
       5. The transceiver of  claim 1 , wherein the code module is configured to generate the space-frequency code matrix such that the OFDM symbol is transmitted with equal power per antenna on the plurality of antennas. 
     
     
       6. The transceiver of  claim 5 , wherein the code module is configured to generate the space-frequency code matrix such that a row norm is equal for each row. 
     
     
       7. The transceiver of  claim 1 , wherein the code module is configured to generate the first vector using permuted space-frequency codes, wherein the space-frequency codes are indicative of different antenna-tone mappings, wherein the antenna-tone mappings map a tone to a portion of the plurality of antennas. 
     
     
       8. The transceiver of  claim 7 , wherein the space-frequency code matrix comprises one of a plurality of permutations of antenna-tone mappings. 
     
     
       9. The transceiver of  claim 8 , wherein the code module is configured to cycle through the plurality of permutations on a tone-by-tone basis. 
     
     
       10. The transceiver of  claim 1 , wherein the code module is configured to generate the first vector using a generalized cyclic delay diversity technique. 
     
     
       11. The transceiver of  claim 1 , wherein the transmit section comprises a modulation module configured to produce one or more modulated symbols, of the second vector, based on the predetermined spatial multiplexing rate r s , and the code module is configured to communicate with the modulation module to receive the one or more modulated symbols. 
     
     
       12. A transceiver comprising:
 a transmit section configured to generate signals for transmission on a plurality of antennas at a predetermined spatial multiplexing rate r s , the transmit section including:
 a code module configured to generate a first vector for a tone in an orthogonal frequency-division multiplexing (OFDM) symbol from a second vector corresponding to the tone and a space-frequency code matrix, the second vector including a number of modulated symbols corresponding to the predetermined spatial multiplexing rate r s , 
 
 wherein the code module is configured to generate the first vector using a generalized cyclic delay diversity technique, 
 wherein the plurality of antennas comprise M T  antennas and the predetermined spatial multiplexing rate r s  has a value between 1 and M T , and 
 wherein the space-frequency code matrix is given by the following equation:
   B k =k M     T     ,r     s   D k F M     T     ,r     s   , 
 
 
       where k M     T     ,r     s    is a normalization constant, F M     T     ,r     s    is a Fourier sub-matrix consisting of the first r s  columns of an M T -point discrete Fourier transform, and D k  is a diagonal matrix of exponentials that are a function of a cycle delay on each of the plurality of antennas, and is given by the equation:
   D k =diag{e −j2πkL     i     /N } i=0   M     T     −1    
 
       where L i  is a cyclic delay for an i-th antenna, and N is the size of an inverse fast Fourier transform (IFFT). 
     
     
       13. A method comprising:
 generating i) a first vector for a tone in an orthogonal frequency-division multiplexing (OFDM) symbol from a second vector corresponding to the tone and ii) a space-frequency code matrix, the second vector including a number of modulated symbols corresponding to a predetermined spatial multiplexing rate r s ; 
 processing the first vector for transmission on a plurality of antennas at the predetermined spatial multiplexing rate r s ; and 
 generating the space-frequency code matrix such that a Frobenius norm of the space-frequency code matrix is constant for all tones. 
 
     
     
       14. The method of  claim 13 , wherein the plurality of antennas comprise M T  antennas and the predetermined spatial multiplexing rate r s  has a value between 1 and M T , and
 wherein the space-frequency code matrix comprises an M T ×r s  matrix. 
 
     
     
       15. The method of  claim 14 , wherein the first vector includes M T  symbols. 
     
     
       16. The method of  claim 13 , wherein the OFDM symbol includes a plurality of tones, and
 the method further comprises generating the space-frequency code matrix such that the OFDM symbol is transmitted with equal transmit power per tone on the plurality of antennas. 
 
     
     
       17. The method of  claim 13 , further comprising:
 generating the space-frequency code matrix such that the OFDM symbol is transmitted with equal power per antenna on the plurality of antennas. 
 
     
     
       18. The method of  claim 17 , further comprising:
 generating the space-frequency code matrix such that a row norm is equal for each row. 
 
     
     
       19. The method of  claim 13 , further comprising:
 generating the first vector using permuted space-frequency codes, wherein the space-frequency codes are indicative of different antenna-tone mappings, wherein the antenna-tone mappings map a tone to a portion of the plurality of antennas. 
 
     
     
       20. The method of  claim 19 , wherein the space-frequency code matrix comprises one of a plurality of permutations of antenna-tone mappings. 
     
     
       21. The method of  claim 20 , wherein generating the first vector comprises:
 cycling through the plurality of permutations on a tone-by-tone basis. 
 
     
     
       22. The method of  claim 13 , further comprising:
 generating the first vector using a generalized cyclic delay diversity technique. 
 
     
     
       23. A method comprising:
 generating a first vector for a tone in an orthogonal frequency-division multiplexing (OFDM) symbol from a second vector corresponding to the tone and a space-frequency code matrix, the second vector including a number of modulated symbols corresponding to a predetermined spatial multiplexing rate r s ; 
 processing the first vector for transmission on a plurality of antennas at the predetermined spatial multiplexing rate r s ; and 
 generating the first vector using a generalized cyclic delay diversity technique, 
 wherein the plurality of antennas comprise M T  antennas and the predetermined spatial multiplexing rate r s  has a value between 1 and M T , and 
 wherein the space-frequency code matrix is given by the following equation:
   B k =k M     T     ,r     s   D k F M     T     ,r     s   , 
 
 
       where k M     T     ,r     s    is a normalization constant, F M     T     ,r     s    is a Fourier sub-matrix consisting of first r s  columns of an M T -point discrete Fourier transform, and D k  is a diagonal matrix of exponentials that are a function of a cycle delay on each of the plurality of antennas, and is given by the equation:
   D k =diag{e −j2πkL     i     /N } i=0   M     T     −1 , 
 
       where L i  is a cyclic delay for an i-th antenna, and N is the size of an inverse fast Fourier transform (IFFT). 
     
     
       24. A tangible non-transitory machine-readable medium embodying a computer program operable to cause one or more machines to perform operations comprising:
 generating i) a first vector for a tone in an orthogonal frequency-division multiplexing (OFDM) symbol from a second vector corresponding to the tone and ii) a space-frequency code matrix, the second vector including a number of modulated symbols corresponding to a predetermined spatial multiplexing rate r s ; 
 processing the first vector for transmission on a plurality of antennas at the predetermined spatial multiplexing rate r s ; and 
 generating the space-frequency code matrix such that a Frobenius norm of the space-frequency code matrix is constant for all tones. 
 
     
     
       25. The tangible non-transitory machine-readable medium of  claim 23 , wherein the plurality of antennas comprise M T  antennas and the predetermined spatial multiplexing rate r s  has a value between 1 and M T , and
 wherein the space-frequency code matrix comprises an M T ×r s  matrix. 
 
     
     
       26. The tangible non-transitory machine-readable medium of  claim 25 , wherein the first vector includes M T  symbols. 
     
     
       27. The tangible non-transitory machine-readable medium of  claim 24 , wherein the OFDM symbol includes a plurality of tones, and
 further comprising generating the space-frequency code matrix such that the OFDM symbol is transmitted with equal transmit power per tone on the plurality of antennas. 
 
     
     
       28. The tangible non-transitory machine-readable medium of  claim 24 , further comprising:
 generating the space-frequency code matrix such that the OFDM symbol is transmitted with equal power per antenna on the plurality of antennas. 
 
     
     
       29. The tangible non-transitory machine-readable medium of  claim 28 , further comprising:
 generating the space-frequency code matrix such that a row norm is equal for each row. 
 
     
     
       30. The tangible non-transitory machine-readable medium of  claim 24 , further comprising:
 generating the first vector using permuted space-frequency codes, wherein the space-frequency codes are indicative of different antenna-tone mappings, wherein the antenna-tone mappings map a tone to a portion of the plurality of antennas. 
 
     
     
       31. The tangible non-transitory machine-readable medium of  claim 30 , wherein the space-frequency code matrix comprises one of a plurality of permutations of antenna-tone mappings. 
     
     
       32. The tangible non-transitory machine-readable medium of  claim 31 , wherein generating the first vector comprises:
 cycling through the plurality of permutations on a tone-by-tone basis. 
 
     
     
       33. The tangible non-transitory machine-readable medium of  claim 24 , further comprising:
 generating the first vector using a generalized cyclic delay diversity technique. 
 
     
     
       34. A tangible non-transitory machine-readable medium embodying a computer program operable to cause one or more machines to perform operations comprising:
 generating i) a first vector for a tone in an orthogonal frequency-division multiplexing (OFDM) symbol from a second vector corresponding to the tone and ii) a space-frequency code matrix, the second vector including a number of modulated symbols corresponding to a predetermined spatial multiplexing rate r s ; 
 processing the first vector for transmission on a plurality of antennas at the predetermined spatial multiplexing rate; and 
 generating the first vector using a generalized cyclic delay diversity technique, 
 wherein the plurality of antennas comprise M T  antennas and the predetermined spatial multiplexing rate r s  has a value between 1 and M T , and 
 wherein the space-frequency code matrix is given by the following equation:
   B k =k M     T     ,r     s   D k F M     T     ,r     s   , 
 
 
       where k M     T     ,r     s    is a normalization constant, F M     T     ,r     s    is a Fourier sub-matrix consisting of first r s  columns of an M T -point discrete Fourier transform, and D k  is a diagonal matrix of exponentials that are a function of a cycle delay on each of the plurality of antennas, and is given by the equation:
   D k =diag{e −j2πkL     i     /N } i=0   M     T     −1 , 
 
       where L i  is a cyclic delay for an i-th antenna, and N is the size of an inverse fast Fourier transform (IFFT).